CVE-2023-40581

yt-dlp is a youtube-dl fork with additional features and fixes. yt-dlp
allows the user to provide shell command lines to be executed at various
stages in its download steps through the --exec flag. This flag allows
output template expansion in its argument, so that metadata values may be
used in the shell commands. The metadata fields can be combined with the
%q conversion, which is intended to quote/escape these values so they can
be safely passed to the shell. However, the escaping used for cmd (the
shell used by Python’s subprocess on Windows) does not properly escape
special characters, which can allow for remote code execution if --exec
is used directly with maliciously crafted remote data. This vulnerability
only impacts yt-dlp on Windows, and the vulnerability is present
regardless of whether yt-dlp is run from cmd or from PowerShell.
Support for output template expansion in --exec, along with this
vulnerable behavior, was added to yt-dlp in version 2021.04.11. yt-dlp
version 2023.09.24 fixes this issue by properly escaping each special
character. \n will be replaced by \r as no way of escaping it has been
found. It is recommended to upgrade yt-dlp to version 2023.09.24 as soon as
possible. Also, always be careful when using --exec, because while this
specific vulnerability has been patched, using unvalidated input in shell
commands is inherently dangerous. For Windows users who are not able to
upgrade: 1. Avoid using any output template expansion in --exec other than
{} (filepath). 2. If expansion in --exec is needed, verify the fields you
are using do not contain ", | or &. 3. Instead of using --exec, write the
info json and load the fields from it instead.

Notes